Doesn't really matter if people earn more money on youtube, they will switch. On Android, not a lot of people are sideloading most prefer the App Store even if they also take a steep cut.
I don't think that's comparable at all. Patreon is an entrenched 1:N (one website for many creators) method for giving money to your favorite youtube creators; youtube's new system is late to the game. Youtube is late to the game here in the same way that Amazon's Appstore was late to the game on Android (which I think maps better to this scenario than generic sideloading, since both Play Store and Amazon Appstore are both 1:N app distribution methods, just as Patreon and youtube are now.)
You also get "stickers" that highlight your comments/chat which is also a value only the native platform can give you.
As for discoverability, you discover patreon accounts by viewing the videos of creators on youtube. Unless youtube starts banning links to Patreon (this would be evil, but I wouldn't put it past them), there isn't a discoverability problem.